The engineering of synthetic nanostructures for biomedical or bioelectronic applications is likely to require the use of multiple building materials, just as living systems rely on nucleic acids for information content and proteins for chemical and functional diversity. As such, it is critical to advance the science of self-assembly in multiple biochemical realms. To date, only DNA has seen extensive use as a building material for studies of self-assembly, selected for the well-understood and robust structural specificity of sequence recognition. DNA sequences that form two-dimensional arrays, a three-dimensional octahedron, and even enzyme-like structures have been described. Recently, the greater richness of RNA secondary structure has been exploited to create intricately patterned nano-building blocks.
Nucleic acids, however, play a secondary role in biological nanomaterials. Following nature's lead, several early efforts to design self-assembling protein architectures have been described. To date, these synthetic protein assemblies have chiefly recapitulated biological assembly mechanisms, forming filaments from self-complementary β-strands, coiled coils, or helix bundles, or symmetric nanostructures assembled from naturally multimeric proteins.
Designing and producing biological based assemblies that can be used for the fabrication of advanced materials is a rapidly advancing area of research. Self-assembling DNA and protein biomolecular building blocks have been used to produce a number of novel nanomaterials that may be applied to microelectronics, tissue engineering and drug delivery. Because of the well-understood set of rules governing nucleic acid duplex assembly, substantial advances have been made toward the development of DNA based nanostructures. Although the potential for a greater variety of structural and, therefore, functional uses can be envisioned for protein based materials, current methods are highly idiosyncratic to the protein monomers of choice, as well as unable to provide readily available homogenous materials.
Thus, the adaptation of protein nanostructures into useful tools will require further advances in the preparation of homogeneous components, as existing methods have not fully addressed the challenges of both polydispersity and incomplete assembly. Additionally, there is broad interest in methods capable of reliable patterning materials on the 5-50 nm scale, a size regime inaccessible to current techniques.
Thus, there is currently a need for protein-based nanostructures.